The worlds demand of process oil is estimated around 1,000,000 ton per year, including the European that consumed about 250,000 ton. This process oil consists of various types, such as DAE, residual aromatic extract (RAE), mild extraction solvate (MES), and naphthenic oil.
In the latest development of process oil utilization in rubber industry, there is effort by the European Commission to restrict the use of process oil since it is categorized as carcinogenic substance. The European Commission has published restriction order 2005/69/EC (European legislation) about the level of carcinogenic compound in process oil that consist of eight types polyaromatic hydrocarbon (8 Grimmers PAH) with amount of less than 10 mg/kg, wherein one of them is Benzo(a)pyrene (BaP) with amount of less than 1 mg/kg. The limit of 8 Grimmers PAH are assumed equivalent to polycyclic aromatic (PCA) content less than 3% weight. This regulation is effective on 1 Jan. 2010. The eight (8) substances of PAH, referred are Benzo(a)pyrene(BaP), Benzo(e)pyrene(BeP), Benzo(a)antracene(BaA), Chrysene(CHR), Benzo(b)fluoranthene (BbFA), Benzo(j)fluoranthene(BjFA), Benzo(k)fluoranthene (BkFA) and Dibenzo(a,h)antracene (DBAhA). The Measurement of 8 Grimmer PAH content can be conducted by means of Gas Chromatography Mass Spectrometer Isotope dilution method (GCMS-SIM), while PCA content can be analysed gravimetricaly according to IP-346 method.
The challenges that may arise as the consequence of the European legislation mentioned above is that rubber industries need to conduct adjustment in the course of their production, such as change the resulted DAE into alternative products like TDAE, treated residual aromatic extract (TRAE), MES, and naphtenic oil. This adjustment will cause additional production costs which vary depending on the type of alternative process oil being produced. The lowest additional production cost may be obtained when TDAE type of process oil is chosen.
Many efforts to produce alternative process oil have been conducted, especially utilizing liquid-liquid extraction method to produce TDAE with an objective to reduce level of PCA compound up to less than 3% weight. In the present invention the IP-346 analysis method can only measure the amount of PCA compound as a group of aromatic compound, though the group of PAH compound that contained in the group of aromatic (PCA) must be analyzed, as well.
One of the important consideration published in the European Commission 2005/69/EC (European legislation) confirmed the restriction that the level of 8 Grimmers PAHs especially Benzo(a)pyrene (BaP) with amount exceeding the allowed limit will be considered as carcinogenic, mutagenic and toxic, and thereby will be prohibited to produce and distribute within the European legislation area. The presence of PAHs can be detected qualitatively and quantitatively using Benzo(a)Pyrene (BaP) as marker. Commonly known method to measure carcinogenic and mutagenic compound is ASTM E 1687-98 method (Ames test method for determining carcinogenic potential of Virgin Base Oils in Metalworking Fluids) and also Ames test based on OECD Guidelines for Testing of Chemicals No 471(1997). In the present invention method of AMES test using Salmonella typhimurium TA 1535 as microbes that is very sensitive to mutagenic compounds.
In this invention Gas Chromatography Mass Spectrometer (GCMS) based on isotope dilution methods have been applied to analyze and calculate the PAH contained in the DAE Feed and TDAE products.
Former method relates to process oil production which is closest related to the present invention is that of EP 0417980A1. In this European patent document, the feed that is used is an extract with kinematic viscosity value at temperature of 100° C. is limited to a value of 30.5 cSt whereas in the present invention is more flexible since the extract feed being used have kinematic viscosity values at temperature 100° C. ranges from 5 to 100 cSt, preferably between 10 to 80 cSt, and more preferably 15-70 cSt. Still in the patent document EP 0417980A1 it is found that the method of processing that is used is highly complicated, for example it requires very tight control on the temperature system and the occurance of pseudo-raffinate flow. Both of this conditions need special equipments and energy, whereas in the present invention the diluent used can simplify the flow of process, so that liminate the pseudo-raffinate flow which occurs in the European Patent EP 0417980A1. This European patent document describes that the tight control of temperature in the extraction column ranges from 50 to 90° C. on the upper portion of the column and 20 to 60° C. in the lower portion of the column. This case does not happen in the present invention since the temperature is controlled isothermically in the whole of extraction column at 22-35° C. (ambient temperature) so that the expenses for processing become cheaper than that of European Patent EP 0417980A1. In the former related method which is mentioned in the American Patent Document U.S. Pat. No. 6,802,960 B1 it is stated that component of aromatic compounds content in the second extract product is minimum 20% weight, whereas in the present invention the component of aromatic compound is larger than 25% weight, even can reach as much of 30 to 37% weight.
Note that the reference used in the production of TDAE of the prior arts is PCA compound with maximum content of 3% weight, whereas in the present invention the effort to fulfill the requirement of 8 Grimmer PAH in the level of PCA less than 3% and in the PCA level ranges from 3% to 20% weight is more preferred.